1. Field of the Invention
The present invention relates to a supporting structure of a vibrator, and more particularly, to the supporting structure of the vibrator used in a vibrating gyroscope applicable in a navigation system, which detects a rotational angular velocity to locate a moving body for adequate guidance, or in a damping system such as an anti-hand-vibration device which detects an external vibration for adequate vibration control.
2. Description of the Prior Art
FIG. 5(A) is a perspective view showing an example of a conventional vibrating gyroscope which is a background of the present invention, and FIG. 5(B) is a sectional view taken along a line VB--VB of FIG. 5(A). The vibrating gyroscope 1 comprises a vibrator 2. The vibrator 2 includes, for example, a substantially regular triangular prism-shaped vibrating body 3. On three side faces of the vibrating body 3, piezoelectric elements 4a, 4b and 4c are formed respectively. The three piezoelectric elements 4a, 4b and 4c include piezoelectric layers 5 respectively consisting of ceramics and the like. On both faces of the piezoelectric layers 5, electrodes 6 are formed respectively. One side of the electrode 6 is bonded to the vibrating body 3 by means of adhesives and the like. Meanwhile, on a ridge-line portion in the vicinity of two nodal points of the vibrating body 3, two supporting members 7a and 7b are secured respectively. The two supporting members 7a and 7b are formed with, for example, a substantially U-shaped metal wire, and are secured to the vibrating body 3 by means of welding or adhesives. The supporting members 7a and 7b are arranged such that, their end portions extend in a direction perpendicular to an axis of the vibrating body 3. The end portions of the supporting members 7a and 7b are fixed to a supporting base plate (not shown).
In the vibrating gyroscope 1, an oscillation circuit (not shown) is connected between the piezoelectric elements 4a, 4b and the piezoelectric element 4c. The vibrating body 3 is bent and vibrated in a direction perpendicular to a face of the piezoelectric element 4c by the oscillation circuit. When the vibrating body 3 rotates about its axis in this state, the bending and vibrating directions change due to a Coriolis force. Thereby, a difference between output signals of the piezoelectric elements 4a and 4b is produced. Thus, a rotational angular velocity can be detected by measuring the output voltage difference between the piezoelectric elements 4a and 4b.
When applying the vibrating gyroscope 1 to a navigation system of an automobile, the vibrating body 3 is arranged such that its axis is directed in a perpendicular direction, as shown in FIG. 6, to detect a rotational direction of the automobile.
However, due to uneven road conditions, the automobile tends to vibrate in the perpendicular direction. In the case of arranging the axis of the vibrating body 3 in the perpendicular direction, the two supporting members 7a and 7b are arranged in a horizontal direction. And hence, the strength of the two supporting members 7a and 7b becomes weaker against a vibration in the perpendicular direction. Since the two supporting members 7a and 7b are fixed respectively to the vibrating body 3 or the supporting base plate, fixing works tend to increase.